Process of drying laminated paper material or boards



.Oct. 16, 1934. 1c, CORCORAN 1,977,045

PROCESS OF DRYING LAMINATED PAPER MATERIAL OR BOARDS Filed Sept. 12 1931ii?? i. {Ema/n21.

Patented Oct. 16, 1934 UNITED STATES PATENT OFFICE PROCESS OF DRYINGLAMINATED PAPER MATERIAL OR BOARDS John C. Corcoran, Worcester, Mass,assignor to Superior Tool & Manufacturing (10., Inc., Worcester, Mass acorporation of Mmhllr' setts The present invention relates to themanufacture of laminated paper material known in the art as boards" ofvarious kinds, such as have been made by building up layers of paper ona wet machine until the desired thickness of board is secured, or bysuperposing separate sheets of paper with adhesive therebetween. Theobject of the present invention is to provide an improved process-ofdrying sheets of paper boards 0 in such a manner as to deliver the driedboards in flat condition.

In the manufacture of paper boards of various kinds, as previouslycarried out, it has been customary to dry the separate sheets by merely.5 hanging the same so as to be suspended in the air, and it has beenfound that this manner of drying the sheets often causes them to warpand twist out of shape. Since any appreciable warping or twisting of thesheets of board renders them unsuitable for commercial use, it hasheretofore been necessary to flatten the sheets after drying, therebyadding materially to the cost of production.

According to the present invention, there is 25 provided an improvedprocess of drying built up paper boards of various kinds-characterizedby the progressive drying of the boards while preventing any warping ortwisting of the same, so that the dried boards are delivered in fiatconso dition. The above and other advantageous features of the inventionwill hereinafter more fully appear from the following description withreference to the accompanying drawing, the single\ figure of which is adiagrammatic representation of one arrangement of instrumentalities forcarrying out the process.

Referring to the drawing, a number of rotatably mounted drying cylinders1, 1 are provided, around which pass drying aprons 2 and 3, preferablycomposed of felt. The aprons 2 and 3 pass back and forth between thecylinders 11, 1 in contact throughout, suitable tension devices 4 beingprovided above and below the cylinders for keeping the aprons taut. Thelower apron 2 extends beyond the front cylinders l, where it passesaround a guide roll 5, thereby providing a board receiving portion 241that is entirely free from the downwardly moving upper apron 3.

-5 The other end of the apron 2 is extended beyond adapted to be heatedin any suitable manner, as by the admission of steam thereto.

In carrying out the process of the present invention by means of thearrangement of appsratus described above, sheets of board 9 such as havebeen formed on a wet machine by building up layers of paper, or such ashave been formed by superposing separate sheets of paper with adhesivetherebetween, are delivered one by one in a moist condition to thereceiving portion 2a. of

the lower drying apron 2. Movement of the receiving portion 2a of theapron in the direction of the arrow will carry each board 9 into thebight between the two aprons 2 and 3 as the aprons pass around thelowermost drying cylinder 1. As the sheets of board 9 enter between theaprons 2 and 3, the sheets are held tightly in place, without anypossibility of warping or twisting, and are maintained in this conditionas the aprons pass around the drying cylinders 1. It is evident from aconsideration of the drawing that the cylinders 1 are arranged in such amanner that first one side and then the other of each sheet of board iscurved around a drying cylinder, so that the drying takes place evenlydue to the reversal of the sheet with respect to the heated surfaces ofthe cylinders. Throughout the travel of each sheet of board, it is neversubjected directly to the heated surface of a cylinder, due to one orthe other of the interposed aprons which extract the moisture of theboards and evaporate the same.

Obviously, the evaporation of the moisture taken up by each apron iscarried out evenly, since portions of first one apron and then the otherare alternately exposed to a heated cylinder and then to the air. asthey pass around the cylinders. It has been found that the pyramidalarrangement of the drying cylinders, as shown on the drawing, insures amaximum degree of contact between the aprons and the cylinders, withopportunity for the surfaces of both aprons to be subjected to thedrying action of the air, both above and below the cylinders.

After passing completely through the rolls while confined between thedrying aprons 2 and 3, each sheet of board 9 emerges from between thebight of the aprons at the lowermost cylinder 1 and rims out in anabsolutely flat condition to the horizontal delivery portion 2a of thelower apron. By this time the sheet of board is thoroughly dry, and themovement of the apron portion .2ain the direction of the arrow deliverseach board to the table '7 in an absolutely flat condition.

From the foregoing, it is apparent then that by the present inventionthere is provided an improved process of drying built up paper boards ofvarious kinds, so that each sheet of board is delivered thoroughly driedand in a flat condition. Furthermore, each sheet of board resulting fromthe practice of the process is of uniform character throughout, owing tothe travel of the board between the aprons with first one side and thenthe other subjected to the drying effect of a heated cylinder. While Ihave shown a preferred arrangement of apparatus for carrying out theinvention, obviously such apparatus is susceptible of modificationwithout departing from the principle underlying the process, as setforth in the appended claim.

JOHN C. CORCORAN.

